How the Tesla Semi “Broke the Laws of Physics”
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- เผยแพร่เมื่อ 10 มิ.ย. 2024
- When Tesla unveiled their Semi 5 years ago, auto industry was skeptical to say the least. As Daimler put it, Tesla must be defying the laws of physics.
In this video we'll look at how the Tesla Semi "Broke the Laws of Physics"
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Timeline
00:00 Intro
01:09 Drag Coefficient
02:05 Powertrain
03:31 Tesla’s 20% Advantage
04:36 The Plaid Motor
06:56 The Limiting Factor for Regen
10:53 1000 Volt Triangle
11:49 Summary
Intro Music by Dyalla: Homer Said - วิทยาศาสตร์และเทคโนโลยี
Read before commenting on regen and 17% cost advantage:
1) At 12:35 I say that the Semi recaptures 90%. Obviously this is one way efficiency. The round trip efficiency would be 81% because it has to go from battery to wheel and then wheel to battery. More on this in the next video.
2) A lot of people are thinking the 17% cost estimate is mine. It's from Tesla - directly from their unveiling event. Cleanerwatt did an update of this on his channel, go check it out. th-cam.com/video/WIzcaBSFud8/w-d-xo.html
Is it possible that rather than treating the battery as a single unit Tesla could be say dividing the battery into say 9 sections of 100 kWh each and alternately using one of those sections to power the vehicle and be available for recharge, rotating these sections to increase life cycle.
@@jjamespacbell good idea
@@jjamespacbell woudlnt it be better against degradation if enery divided into more cells?
The carbon wrapped plaid motor was an innovation subsequent to the original concept. Tesla has a talent for leveraging luck...😉
@@davincisghost9228 More engineering intelligence and talent than luck.
Great analysis, thanks. It is ridiculous that anyone calls it "breaking the laws of physics". Certainly not physicists. Physics does not impose any limit on how far can a car or truck go. With no energy losses in ideal conditions the truck could literally go forever, this is not realistic of course but with technology you can get closer and closer. The only limit is only technological.
No, because of air friction.
@@pilotavery That's why I specified "with no losses in ideal conditions". Air sure is a limiting factor. And so is rolling resistence and bunch of other stuff. The point is you can get better and better in all of the limiting factors and we are nowhere near what physics allows. The techonology is limited.
@@RandomGuyOnTH-cam601 technology is improving constantly! We went from nothing to wheels, assisted steering, ABS, seatbelts……
There are certain physical limits to a truck that conforms to legal limits. Rubber on asphalt is always going to have a certain coefficient of drag >0 and with a weight m on even ground, you'll always have to overcome a rolling resistance of Crr*g*m, no matter what. A semi is also always going to have a maximum length, which means your frontal area is can't get smaller without reducing volume.
@@plainText384 lol….. improvements are always made doesn’t matter if huge or small!
Every minute of every Limiting Factor video is appreciated. Thank you for your unparalleled efforts and unique content.
Except the bullshit on cargo capacity, it's max cargo capacity is 1/2 a diesel semi and on that hill climbing video it's carrying 5 ton while the diesel is carrying 20 ton. Short range electric semi is great, Tesla's is a joke.
@@drac410 please recheck your very flawed math. The max cargo capacity of the Tesla is the same as a diesel thanks to the ax weight being 82,000 lbs making up for the weight difference with a diesel semi. And that’s the 500 mile version. And it’s range is 500 miles fully loaded at 82,000 lbs.
A good example of first principle thinking at Tesla is adding a automatic tire inflation system to the semi. I guess, this allows to keep the tire pressure within narrower limits, so the rolling resistance is as low as possible. The rolling resistance of a loaded truck is quite high.
It will also reduce tire replacements. The tires are huge and thick with lots of hysteresis so I imagine temperature changes often push the actual inflation pressures outside of ideal limits during a run. Having perfect pressure constantly will reduce tire wear and increase safety as well as optimizing rolling resistance. We've all seen the remnants of peeled and blown truck tires on the highways.
Hardly new or unique technology. You can buy it off the shelf in Europe.
WoW,
I am not an engineer, just deeply interested in how Tesla makes its magic. Your technical level is in the perfect pocket for what I can handle. Second, your explanation of the Semi's regen braking advantages are the BEST BY FAR that I've seen. Bravo & thanks!
This is not magic lol….
All EVs have Regen braking lol!!!!! Wtf!!
Excellent content!
Demonstrating the compounding "interest" of efficiency gains in regenerative energy's life cycle is visualized well in your presentation.
The effect of parallel systems (larger battery, added motors) on the total system's efficiency makes so much sense. The added performance is really just a nice windfall of reaching for this level of efficiency.
Well said!
Unfortunately that power is totally useless! You are comparing a 1020hp truck to 500ho diesel, a 750hp Volvo diesel truck hauls about 4x 5€3 load of tesla and that’s accross the outback.
And added weight...
The 500 mile pack will be very useful for last-mile deliveries, for most firms that cannot afford a megacharger. For example, a truck years ago delivered pallets to our small warehouse. The driver said I was the last stop of 11 that day, returning to his Richmond VA hub 56 miles away, with an empty tank. Most days were 200 to 300 miles, getting better MPG as it gets lighter.
The payback on a Megacharger will be very quick when diesel fuel is $5+/gallon. Most firms won't be able to afford NOT having one.
@@SomeTechGuy666 Yes you are right, IF you can afford it. One megacharger costing $2M can handle 10+ trucks a day. But small trucking firms don't have 10 trucks or $2M. So they will borrow one or slow charge overnight. (Elon Musk and his brother rented a cheap office for his first company in the 90s, says Ashlee Vance. Apple was started in a garage).
yeah, good truck to drive battery around 😂
I'm from Richmond
@@SomeTechGuy666 Except they don't exist yet and a single one would require it's own substation.
You can bet your boots they'll use the same tech in the Cybertruck. Recapturing the enormous amount of inertia from a heavy vehicle is absolute genius.
Not to mention that even 3 motors would be huge overkill.
I would imagine a single on the front for "cruise", dual on the rear for "beast mode"
Or just plain good engineering.
I object to betting Boots, but I do have a cybertruck on order so I hope you're right!
You recapture energy from *momentum*, not inertia. Inertia is not momentum.
All Tesla models have regen braking, you hardly need to use the brakes. The regen braking uses captured energy to recharge the battery. In an ICE braking it’s lost as heat.
Thank you, great work IMO. A plausible extrapolation based on the information that was available. I look forward to updates as you get access to more information.
Thanks Jordan. I agree with your reasoning on why Tesla uses 3 motors.
@The Limiting Factor That was an excellent video...Thanks for making this presentation.
This was a VERY interesting listen. Thank you!
Awesome, I am always super excited to see a new video from you! I love the well researched in depth analysis, and that you give it to us straight, no rose colored glasses!
I watch and like Tesla "news" channels, but ones like yours with in-depth breakdowns and analysis are more informative on a fundamental level. Also, much harder to make. Lastly, very nerd friendly. ;^)
😁
Thank you for this instructive and comprehensive video😃🙏🏼!
Thanks, this answered several questions I had! Excellent work!
Incredible! Thank you. The battery charge capacity vs regeneration never occurred to me.
The Semi is indeed mind bending!
This is one of your best videos. Well done!
Thanks Peter!
An excellent video, sir. Thank you again for sharing your insight.
Another great presentation - very thoughtful and intelligent analysis! Congrats on getting close to 100,000 subscribers! Rooting for you to get over that milestone!
This was a very informative piece. Thanks! The small things add up to a big thing. Also, not included in these numbers are the money operators will save with not having to replace oil, filters, and break pads.
Don't forget the time element in those replacements.
And even brake pads!
Such well researched info. Good video
Very engaging and enlightening video!
Your videos are outstandingly good! The amount of information you cover in this short video is better than all of Tesla semi videos and tweets I've read over the past 4-5 years combined.
I aim to please, lol
Very well put together, you never fail to impress.
Very informative, thank you 👍
Super work as usual! Much appreciated!!
This is so cool. Sometimes your video's are so full of information my head just explodes when I can't connect it to somthing I know. Last week I had an exam about electromechanical drive technologies and now I could connect the information to what your trying to tell us. This is so amazing. Thank you!
😁😁
_"...your video's are so full of information my head just explodes..."_
That's intented distraction from basic physics and the important stuff.
I love your videos. They are one of the most informative, fact dense and professional videos. Keep up the great work. 👍👍👍
Beautiful analysis. Thank you!
Great educated speculations and insights Jordan 👍
Great inside! The regen idea and direct drive use of the motors on their peak efficiency is genious.
Its also genius.
Just like in all EVs with awd! Lol…. Use your brain!!! awd isn’t active all the time!
Excellent video, thanks! As you said, the 'limiting factor' for regenerative braking is the battery. Bigger batteries can accept more Kw from the motors in 'regen' mode.
This has a lot of advantages: longer battery life, higher recuperation of energy, less stress on single battery cells, faster charging time..
And last but not least more security because Tesla Semi brakes will not be needed very often!
So you somehow forgot the drawbacks?
Higher cost
More risk if it catches fire
Huge amount of extra weight
More charge time.
Tesla vehicles are a lot less likely to catch on fire than the average gas car. Extra weight in battery but the government grants electric trucks an extra 2,000 pounds, and there are some weight reductions in not having a giant engine. Overall the difference is minor. Charge time is surprisingly short. They redesigned their chargers and even added water cooling in order to charge these bad boys quickly.
Have you seen the cost of new semis’? Difference isnt that great, and the reduced maintenance costs and cost per mile means that it is worth it for many. Time will tell.
@@R1L1. Diesel trucks also catch fire, which sometimes result in dozens of death, as what happened in Mont-Blanc tunnel, close to where I live. Actually, gasoline or diesel-fueled vehicles catch fire much more often than later-generation electric ones, especially Teslas.
What huge amount of extra weight? As mentioned in the video, the Semi's payload is within 1-1.5 ton of a diesel rig in the USA, and actually even a bit higher in Europe, due to a larger max weight allowance for electrical trucks.
More time to charge than to fill-up? Yes, correct... but except for team operations, the amount of hours a truck can move every day is limited by the driver's legal driving hours, not the battery's charging time.
Higher costs? The ticket price may indeed be higher, but what counts to a trucking company is overall costs. And in that, the Semi will excel!
Nailed it Jordan! Great vid!
You do a very therow job on your videos.
Thanks for the update on the semi.
A truly breathtaking analysis that made the impossible appear "obvious" after the fact. To capture the regenerative breaking from a heavy fast moving truck going downhill requires massive battery and generator (electric motor) capacity. After the fact: Duh! The other great idea is that the difference between hyper-acceleration a model S Plaid and a heavy semi can be reduced to gearing! (Archimedes would be proud). Great work and I apologize for the "Duh" that is only after you brilliantly explained it.
Pfff, no offense taken! It was cathartic, lol
@@thelimitingfactor
You could say a "Eureka!! moment"? 😁
Lol…. Proud of what!?
Acceleration on trucks is totally useless tbh!
@@alanmay7929 not when going uphill.
I like your theory that the 3 plaid motors are there to increase regen capability of the semi.
Or put another way...
Instead of having 400 hp braking with one motor, you now have 1200 hp braking with 3 motors.
For a couple of hundred lbs in 2 extra motors you get:
- 3 times the acceleration
- More range as you capture more kinetic energy
- Much less brake wear.
You forget that having more peak power also means you don't have to run everything at or near peak power for extended periods of time but at or near peak efficiency most of the time.
An electric power train that is rated for much higher output is just a bit heavier than the weaker one but will waste much less energy in heat losses at the same power output, that's another bonus you get... I just don't know what's more efficient: run all three motors at lower power or decouple two and run the third at higher power.
I would say some of your assumptions may not hold true.
You are automatically assuming that carrying the extra weight of those motors will somehow only be a benefit. If a truck is going to do a lot of start/stop driving like buses then yes it makes sense.
However if a truck is doing a lot of long haul trips then acceleration is really irrelevant, and carrying the extra weight of those motors will probably reduce the range without much benefit.
They are already keeping the weight of the truck a secret, which seems to suggest it is very heavy already. It seems strange they are avoiding mentioning the weight of the truck, especially since its one of the most important stats.
Killing it! Always killing it. Thank you
Thanks for the knowledge.
I want to see the speed synchronization system between the motors and roadwheels (drive axles)
That's going to be a "KISS/ Facepalm" moment for transmission designers everywhere.
I imagine simply
1)monitor axle rotation speed
.
2) Spin motor to appropriate revs
.
3) Engage solenoid. Drive dogs engage.
No "clutch" required
Its been done in hybrid propulsion systems in the marine industry (in transferring between motors and engines).
Are you sure there is no clutch and clutch face?
@@bru512
Watch the animation
Agree, no doubt...
@@rogerstarkey5390 Ok, I am convinced there is no clutch plate. Cool & thanks!
As usual, fantastic discussion and full of data driven perspectives
thank you for detailed energy use discussion
Well...what a pleasant surprise!
The semi caught my eye so I just plugged in and watched. Nice content, dude. Very nice. It all fit into my technocrat instincts perfectly.
Logical result: Subscribe and white bell plus thumbs up for each of your efforts. Thank you!
Now I'm off to find the start and binge for a while. With three score and 16 behind me, retirement permits such luxuries to a nocturnal such as I.
When I find Tesla he gets a well-deserved deep bow from me. Literally.
Cheers from Ottawa, ON.
Great content! This is really interesting from the engineering and physics perspective.
Great work as usual Jordan!
I have wondered why they used mechanical clutches to disconnect the dual motors in cruise. If you just leave the motors open circuit they would freewheel anyway. Perhaps back-driving the reduction gears wastes power?
The other thing I have wondered is whether you could dump regen braking power into some supercapacitors. They are able to absorb enormous transient charge currents.
Lastly, the assumption that good regen energy recovery is a cause of the efficiency would only apply in mountainous areas or around town in stop/start traffic. This would not be consistent enough for Tesla to claim a repeatable 500-mile range, right?
Yeah, the motors do create 'drag' Better to disconnect them
I too have thought of the super capacitors that would then charge the batteries… maybe they just want to keep it simple
I think the super capacitors makes a lot of sense. Wonder how that could be incorporated into current EVs because it would be impermanent energy storage that could be transferred to the battery. Removing the limitations of current battery chemistry.
As far a regen it’s always a good efficiency effort as you always have to stop at your destination so the energy needed to stop your vehicle becomes improved efficiency. Variations in elevation are simply the more extreme scenarios that generate more power to offset the increased power demand
@@chidorirasenganz Plus: Tesla bought Maxwell - their main product was supercaps.
@@castletown999 👀 yeah you might be on to something. I need to look back into super capacitors again lol
Excellent video
Nice work thanks
Add up all the small advantage details and the whole product is so far ahead of the competition they can't imagine the results as factual. Well done Tesla! I use to think capacitors would needed to capture large amounts of regenerative energy...looks like this issue has been addressed without any special hybrid battery system. Great report, thanks!
Go Tesla!
As usual, excellent research and summary. Agree that not approaching from first principles as the Tesla Semi team did might lead all others to believe it wasn't possible. Don't bet against Elon.
Fabulous job. Thank you!
Good job as always!!!
I like your triple constraint diagram. It's similar to the classic project management one - time, cost, and quality. "You can have any two, but not all three." Tesla seems to be breaking this axiom but it still largely holds true.
Also, as others have noted below, you do a great job of showing how the counter-intuitive, like a huge battery is more efficient, depending on the use and design, than a small one. This helps explain how Tesla can, "break the laws of physics." More like Daimler's views on physics are simplistic.
Amen!
Larger battery means more weight which decreases max load carrying capacity.
It's not free efficiency gains.
Larger battery also means larger charging times and massive infrastructure to charge them.
It's not free efficiency gains.
The Tesla semi doesn't break the laws of physics. Elons promises do. He says in the same breath that you'll get 500 miles on a charge, and you can go zero to 60 real fast. But you can't do both of those, and literally nobody cares about 0-60 speed in a semi truck.
What is the maximum carrying capacity of a Tesla semi (not including the battery) compared to a diesel semi? If it takes 2 or more electric semis to carry the load that could be carried by one diesel truck, these efficiency gains disappear.
To me, the greatest advantage over Diesel trucks is that EV trucks have regenerative braking. It does not fear climbs as it can always regenerate and recharge when it goes back down the hill.
The problem however is that most of the weight it needs to haul is its own batteries. i.e. not payload.
@@HTOP1982 Wrong again.
You’re dead wrong son
@@HTOP1982 As mentioned in the video, the Semi can carry the same payload, within 1-1.5 ton as a diesel rig. And, as demonstrated by the Tesla video, it can go up, at full load, a 6% incline at double the speed of a diesel truck, and it can also go down faster... that's time saved, at least in hilly country... lot's of it!
Excellent brake-down of the science!
Thank you for the deep analysis.
Greetings,
Anthony
Thanks for addressing this issue Jordon. I hope the folks at Diamlier watch and open up their understanding so that their electric offering can be better.
That was amazing!!! I have checked and found that 80% of semis go less then 300 miles round trip. So local trips are way more important then long haul as far as meeting the needs of the truck companies and owners. This makes so much sense why Tesla makes it happen and no one else can.
It is because they are a Tech companies that makes vehicles and software.
Everybody needs to see this video!!!!
😊
And about 80% don’t max out the weight limit, so that 2 or even 4 tons less weight capacity doesn‘t make a difference in the real world. This Semi will disrupt the trucking industry.
@@user299792 For sure the semis make up only 1% of the vehicles on the road and their pollution is 17%, diesels horrible and kills more people than gas!!
The market is only 250k per year, but in the next five years I believe Tesla will be doing double that number! Once there’s enough Tesla semis out there and the numbers are shown to other companies. they are going to be getting rid of their entire fleet and getting into the Tesla semis. To save money, and to get greener!!
80% of trucks goes more than 300 miles lol…. What types of trucks are you talking about!?
@@MyUniversalUniversity those diesel trucks are also significantly way more useful or flexible than any electric one.
Thanx for ur great research
Thank You for the excellent summary! I now have good talking points for some of my Teskeptical engineering friends
The 1000V battery choice is probably due in big part to the charging power required. Because keeping 400v or 500v would have required twice larger and heavier charging cables and charger connector
Actually I suspect the regen braking demanded the 1000V and the charging was almost as important for speed of charging as you say.
And people were laughing when porsche or lucid choosed those higher voltages!!! Wth!
@@alanmay7929 ... and Hyundai/Kia, which also uses about 1,000 volts.
I’m surprised no one was questioning what the heck Bill Gates knew about EVs and Semi trucks to even be considered a knowledgeable source for any comments.
What amazes me about Bill is that someone who at least in part instigated one of the most disruptive technologies (the most?) of the 20th century seems to have forgotten that disruption happens.
Bill knows a lot about computer viruses....and that made him an 'expert' on human health...apparently!
Very interesting, thank you!
nice work jordan
Favorite podcast Jordan, Tesla blows My mind, it's engineering is phenomenal. Semi is the culmination of everything Tesla's engineer's have learned
old tech lol
Nothing is phenomenal about that! It’s actually lamentable that a 1000hp truck has to compete with 500hp diesel trucks! There are 600hp diesel trucks hauling well over 200,000lbs of loads everywhere. Now a 1000hp diesel truck is for example the TRACTOMAS for very special transport heavy duty
Hey Jordan!
Another good one.
I'd reached the same conclusion regarding the regen. The minimal weight and huge energy transfer capability give a massive advantage.
(I also think "coming to another vehicle soon".....?)
.
😏 Yes...C/t
@@thelimitingfactor
It would be silly not to imo? Overcomes the "towing issue"?
@@rogerstarkey5390 I mean it's not gonna have the huge battery of the semi tho. Wouldn't that throttle the amount of regen in the pack it could get out of the three motors.
Only an advantage when there is a downhill totally useless on flat land
@@alanmay7929 _ totally useless on flat land_
False. Very useful in stop-and-go driving on flat land; this, plus the reduction in aerodynamic drag, is why the city MPGe of almost all EVs is greater than the highway MPGe. It's only cruising at constant speed on flat land that regen braking is useless.
You are correct on the dynamic braking recovery scheme.
The Engineering Explained guy needs to watch your video.
Totally fascinating breakdown (not physically!) I was completely absorbed start to finish! The missing motor is probably the result of Elons Law "The best part is No Part"
Bingo!
That was hardly invented by Elon, just a favorite of his.
Or one motor is just cheaper than two motors.
Good video, but the actual weight of diesel fuel is 7lbs/gallon. So, in your exemplary truck, the actual weight of 150 gallons would be 1,050 lbs., not 500 lbs. That's another 550 lbs. against the diesel powered truck. The weight of the Tesla semi will matter more than you think since the gross weight limit is only 2,000 lbs higher than a conventional diesel powered rig and there are axle sub-limits that may come into play. I suspect the extra 2,000 lbs. will be applied to the truck steer and drive axles and the Tesla semi may weigh more than 2,000 lbs. more than a diesel. So, those per axle sub-limits may affect how much load can be placed on the trailer before the drive axles are hit the limit.
On the other hand, why is the diesel truck carrying 150 gallons of fuel? Yes, they hold that much, but to be comparable to the Tesla Semi it only needs to carry enough to drive 500 miles, which might be half of that much.
@@brianb-p6586 There are no drivers that do that (partially fill the tanks). They do the same thing you and I do when we stop at a gas station in our cars, they fill them up because they don't care about the specs of Tesla trucks and they are rarely close to the 80K GVWR limit. That said, a case could be made for the fact that a diesel truck is only carrying the weight of 150 gallons of fuel when it rolls out of the last fuel stop. From that point on, the weight is diminishing. I didn't bring that up earlier because it wasn't mentioned in the video.
@Greg Scoggins the cargo weight capacity of a truck is limited by the fuel it is carrying when it is loaded; the lower weight later is interesting but of no importance.
@@brianb-p6586 I know how the cargo capacity is affected by the truck & trailer weight, I did about a thousand of these calculations during a 38-year career in the business. I mentioned the poster's mistake in my original post because 550 lbs. can make a difference depending on the situation, especially regarding tractor axle sublimits. Last, your second statement regarding the insignificance of 'lower weight later' is in direct contrast to your original post implying a diesel truck should only carry enough fuel to go as far a Tesla semi that can only go 500 miles.
@Greg Scoggins there's no conflict at all: to maximize cargo load, the diesel should only carry as much fuel as needed (with safe reserve of course, like an aircraft) and doesn't need 150 gallons to be comparable to the EV range; and the reduction in weight as the fuel is burned doesn't matter, because the truck can't take advantage of that by gaining cargo as it drives.
Brilliant analysis :)
Great overview. Technical enough to be interesting without being too technical.
Also, you’re forgetting the efficiency factor for the owner of the truck where the truck can Excelerate uphill rather than coming to a crawl of 10km an hour up inclines, so it will actually get to a destination quicker to load up and turn around and go back
Very good rundown on the Semi! Hope to hear from one of the drivers of Pepsi in the future to get their impressions on how it is like to use the Semi for work, good and bad 👌🏻
wow very good analysis
Jordan, 3xcellent analysis - we need your objectivity and thoroughness. Many thanks, Eamon
In addition to the tractor brakes on a tractor trailer combo, the brakes on the trailer provide additional stopping power. Depending on the hill and the roadway surface conditions, the trailer brakes need to be used in combination with the tractor brakes.
If you brake using tractor brakes alone in some situations you risk a loss of control when the trailer jackknifes because it wants to keep going when the tractor is trying to stop it.
I've drive the various passes in California a lot, including the Grapevine and have seen trucks with brakes on fire before. With good road conditions, could a fully loaded tractor trailer combo rely solely on the tractor brakes going down either side of the Grapevine for maximum regen energy recovery, maybe. But I think there will be conditions where the trailer brake will be needed too, reducing the energy that can be recovered. And there are steeper passes and roads with higher grades than the Grapevine and Cajon pass. The Interstate passes aren't nearly as steep as some of the highway and secondary roadway passes.
Sure... but no one is seriously suggesting not having friction brakes for the times that they are needed. Just as with smaller EVs, regenerative braking can be used in most braking events, and in all cases where a truck would use a compression-release engine brake, without issues.
@@brianb-p6586 Agreed, but recognize that for these steeper passes, the compression brake is no where near enough to hold back a loaded truck.
A related question I have would be how long of a steep grade could be tolerated before the friction brakes need to be employed. Assuming the truck just climbed one side of a long steep grade and has been pulling a lot of power out of the battery and generating a lot of heat in it and the motors in the process, jamming that energy back into the battery at a high rate for an extended period could get the battery and motor even hotter and there is probably some limit.
But, we know the truck just drove the Grapevine on the I-5 with a supposedly max load, so it had to have successfully employed some combination of recovery braking and friction braking. What is unknown is how much of the energy spent climbing the grade was able to be recovered.
But again to my previous point, this only works when surface conditions are good. If wet or snowy, the trailer brakes need to be employed in conjunction with the tractor brakes to keep the rig pointed sunny side up.
@RideGasGas the battery state of charge graph released by Tesla shows that the truck on their 500 mile demonstration drive recovered all available energy on descents by regenerative braking. With regenerative power comparable to drive power, there is lots to control descents. Since it can handle hundreds of kilowatts of sustained charging at a charging station, it can handle sustained regeneration for a long grade.
But yes, if hard enough braking is required (relative to available traction) then the truck should apply the trailer brakes in coordination with the tractor brakes, regardless of whetherthetra tor is using regeneration, friction brakes, or a combination.
@@RideGasGas _A related question I have would be how long of a steep grade could be tolerated before the friction brakes need to be employed._
The Tesla Semi motors, as well presumably as the power electronics, are taken from the Tesla Model S Plaid. The Model S Plaid laps the 13-mile Nurburgring at full throttle most of the way with no heat-related degradation, so presumably the battery, motor and power electronics cooling systems are capable of handling the full 1,020 HP power of the motors and power electronics in either direction, for extended periods. As such, the only real limit would be how steep a grade could be handled, at a given gross weight and speed, without exceeding that rating. Based on the physics of the Tesla Semi derived by MotorMatchup here: th-cam.com/video/zQDU9f4QTLk/w-d-xo.html&ab_channel=MotorMatchup, at 82,000 gross weight, regen braking should be capable of controlling speed to 35 MPH on a -16% slope! Whether that holds in the real world, or there are other physical constraints on this, remains to be seen.
_What is unknown is how much of the energy spent climbing the grade was able to be recovered._
As far as the Grapevine, if you extend the straight line from the first half of the graph of the 500 mile range test here: th-cam.com/video/LtOqU2o81iI/w-d-xo.htmlfeature=share&t=1221, you'll see that after a big drop in Battery % climbing the Grapevine, the blue line is back to that line by the time it gets to Pasadena. On the surface, this suggests that 100% of energy climbing the Grapevine was recovered by the time it gets to Pasadena. Since the theoretical limit is 81%, this is physically impossible. But this is explained by the fact that there's a 35 MPH truck speed limit going up and down the Grapevine; and the reduced losses in aerodynamic drag are about equal to the 20% loss of energy recovered by regen braking. So the net result is that there's little or no loss of range between flat ground, and mountainous terrain.
Yes, just like a diesel semi, trailer brakes would need to be used on low traction situations.
We have developed regenerative trailer axles in Europe ... they power fridge units etc
As battery technology continuously improve, Semi specs will improve. Initially The Tesla semi can focus on Volume limited rather than weight limited payloads. Looking forward to see it on road and disrupt the Diesel semi industry.
Lol….. so they let the diesel trucks still do the dirty job right!? What a pathetic argument! Diesel trucks and equipments are almost used 24/7 to build and maintain roads, bridges, infrastructures, transport and install wind farms and solar farms…..
Thank you!
Excellent analysis.
And extra bonuses with the Semi:
* Reduced braking noise (this is significant)
* Reduced braking particulate emissions
* Loss of braking air pressure is less of an issue
* Three motors offer redundancy in case of a motor fault
With the amount of regen available, a dead stop is easily possible.
.
I'd like to see a clever person work out the theoretical "emergency stop" time/ distance with JUST regen..... 🤔
That would be a great "party piece"?
Imagine a "Regen lockup" stop but with perfectly straight skidmarks?
Yes!
Reduced braking noise (compared to compression-release engine braking) and reduced braking particulate emissions, and less dependence on service brake air pressure are all common advantages of every battery-electric truck over diesels, not unique to Tesla.
A Tesla Semi with a failed motor will be out of service for repair, even with three of them.
Can we take a moment to appreciate that the Tesla semi is basically viable with off- the- shelf components and design? Well, the Tesla shelf, anyway.
The aero design isn't that unusual and could've been roughed out in an afternoon. The frame may simply be a standard configuration, as those have been optimized long ago for the needed strength. The driver cab tech is mostly from their cars, the motors are from their shelf, they're using their old battery tech. Car motors have become powerful and durable enough to use in a million- mile heavy truck!
Off-the-Tesla-shelf components
- Plaid motor
- Battery components
- Inverters
- UI computer
- Drive computer
- ...
This is why Tesla can offer a much lower cost solution than any other other manufacturer
Excellent call-out.
They’re probably not the exact same as the car motors. I would expect a few beefed up components and maybe better cooling to deal with more heavy usage.
@@bru512 Tesla can offer a lot of things, but "low cost" is most definitely not one of them lmao.
Lol….. it’s modified components not just off the shelf!!!
@@bru512 everything modified!!!! It’s not 100% the same hardware! The modelX plaid for example can barely tow 5000lbs while a 200hp diesel car tows well over 7000lbs cab you explain!?
🔥 analysis as always
Thanks for stopping by buddy!
Great work...
truck driver shortage & diesel pollutants will be soon reduced for the benefit of all-Tesla's Sustainable mission is at play.
Fantastic analysis as usual, Jordan! So we would expect the Tesla Semi to be significantly more efficient than Volvo and all the others in any environment when shipping goods over mountainous terrain. The regen should provide way more than a 18% differential. What a stroke of engineering genius that a battery which can accept 770kW regen is paired with a 760kW regen plaid motor.
The the "770kW" regen.
I'll take a bet we see the FUD machine kick in with "OMG!! All that regen will burn out the battery!!!!!"
.
But If we scale it back......
At a "load per cell" level, it's like a 100kWh pack taking a 100kW charge.
.
It's not exactly going to stress the pack?
Do we know that the competition (Volvo etc) don't regen? Genuine question (I can't be bothered to check). If the other guys are not using regen then they should be. But I suspect they are.
@@rogerstarkey5390 100kWh battery 100kW would be a 1C charge rate.
@@chriswright9096 the competition all use regenerative braking, since they're neither ignorant nor idiots. The video just suggests that competing vehicles with smaller battery capacity are more limited in their peak regeneration power by that capacity, which probably makes no difference at all most of the time.
An excellent analysis.
It's always refreshing to watch a video that isn't biased or jumping on a bandwagon of love or hate at any given time. This video simply details how its possible that tesla has done what they've done...love it or hate it. Thank you!
But of course, why would you care what Bill Gates thinks about Tesla feasibility? I don't value his opinion on pretty much anything
Gates was the guy that thought the computer mouse was not needed. Go figure.
@@juliewow4504 I believe he also once said no one will ever need more than 640K of RAM..
Jordan that is an excelent explaination. I think this will respond easy to the publication of Jason from Engineering Explained.
Like everyone he's flawed, but I've never understood the hate of Bill or Elon. I Wish I'd followed his action in shorting Tesla at over $600, I'd have more money to be buying Tesla now.
@@gpsfinancial6988 it's not hate, I just dont value his opinion. His claim to fame is making the worst operating system I've ever had the displeasure of using.
TY
That was also very smooth (fill in the proper word or words here) of #Gained knowledge. 📚 🤗 👌
fantastic video
Can’t wait for the plaid motor deep dive!
Looking forward to the plaid motor deep dive.
As always love your stuff! Keep up the great work! Was surprised by the re-gen info. Love the new info/theory. That’s why I used to watch Gali/Hyperchange. His take was usually unique and didn’t regurgitate the stuff on Elektrek and Teslarati. You are the same if not better! Was surprised by the clutch in the unveiling. Seemed super deliberate. Wonder if it will show up on the Cybertruck. That was the 1st thing I thought of when I saw it. The Cybertruck will probably have a clutch to help add range especially for towing. But maybe I’m wrong about the clutch and Cybertruck
I doubt it will be needed on the Cybertruck.
Excellent!
Will definitely buy asap it is available.
Your observation is on point…
Great video. I agree the use of 3 motors for the main purpose of regeneration is brilliant. I can imagine when Tesla can effectively use the efficiency of the 4680 with lower cell internal resistance they could even improve the regeneration charging capacity and/or even use two and get rid of one motor.
Fascinating!
Thanks for another great video. I am struggling with the M3 AWD power vs. speed curves and also the statement that in track mode the Regen power is 100kW. I've got a lot of data that contradict these two statements. Maybe we can compare the data at some point. Also the Regen power seems to be partly battery limited, which is an easy CAN value that is available, but also runs pretty much negative to the power vs. speed curve. Maximum regen in the same speed region as maximum power, so it is a motor limitation as well.